sometimes no limit is a bad thing (email geekery)
I learned the hard way several times that storing email on the internet is a bad idea, because I've lost thousands of emails that way over the years. You'd think I would have learned my lesson the first time..
Storing mail locally to your computer is a great idea as long as you back it up routinely and use the correct method to store it with.
I truly feel sorry for the poor saps out there that still use Outlook Express 6. Why? Because each mail folder uses a proprietary DBX format for storing mail. If one or more of your DBXs gets corrupted, bye-bye mail. Unless you have a backup, the b.s. you have to go through to get those files working again is just plain ridiculous.
If you use OE6, you are a moron because you're inviting bad things to happen in the future. Switch to Windows Live mail.
Windows Live Mail stores each message individually as an EML file in the store folder it uses, so if you have one email go corrupt for whatever reason, no big deal because it doesn't affect any of your other mail. In addition to that, you can manually repair a corrupted EML by directly editing it with a text editor like Notepad++. That's the beauty of the EML format. Even if a mail gets totally screwed up, you can manually edit to read what it said.
Outlook uses the dreaded PST method of storage, as in one big honkin' file. Yes, there's the repair utility for it, but screw that because it's a 50/50 shot whether it actually works or not.
There is one perk of using Outlook's way of storing mail however - it does have a predefined limit. The latest has a maximum file size of 33TB - and I'm assuming it warns you when you're reaching that limit. In the early-early versions the limit was 2GB.
Thunderbird 2, which is what I use, uses the MBOX database format. This can be edited manually with a text editor in case one of them goes corrupt. But the problem is that if you have to do that, fishing out the corrupt part of the database is a nightmare all its own. You'd have to manually break apart the db in pieces until you found where the corrupt portion was.
I've done some research trying to find out if anybody is aware of a predefined limit for an MBOX database. The answer is always the same - there is no predefined limit.
This is both good and bad.
Good: you can keep piling on data as much as you want without fear of running into a limit.
Bad: You never know how big is too big.
The proper thing to do is to sort mail by year to create separate MBOX files. However this doesn't touch another huge database, the Sent folder. You have to remember to sort out mail by year for that folder as well. My Sent folder is the second largest in my Thunderbird 2.
On top of that, part of the problem with T-Bird 2 is that there is no global search function. Yes, T-Bird 3 has that, but that client sucks.
And on top of that, I don't like running an old email client. When you do that, it makes it more difficult to migrate the data in the future.
What I may be doing in the future is switch back to Windows Live Mail when Wave 4 is released. That client, said honestly, is going to be awesome. It's going to bring in Outlook-esque features (ribbon interface), support tags, social networking updates, and so on. It's all good stuff. Truly.
The only sucky part about switching isn't the mail (because I have a method of exporting all T-Bird mail to individual EMLs for Windows Live Mail import), but rather the contact list. I have to manually put in all the addresses. Frickin' sucks. But oh well, I guess.
WL Mail Wave 4 is something I'm genuinely looking forward to. T-Bird 3 was an absolute disaster, and T-Bird 2 is really long in the tooth. The existing WL Mail is close to everything I want in a mail client, but is missing a few things that keeps me on TB2.
Hopefully when Wave 4 comes out it will be something I can switch to so I can kick Thunderbird to the curb. And I'm pretty sure that's exactly what's going to happen. The TB3 thing was just.. bad. Mozilla had a really good chance of being the free mail client again and botched it up something awful. Now Microsoft is going to step in and stomp Thunderbird into oblivion. I have no doubt of that, because if you've used TB3, you know how much it just plain sucks compared to TB2, and TB2 is old.